Microbial communities around seeds promote Zostera marina germination

Abstract

Eelgrass meadows are vital not only for sustaining marine biodiversity as marine ecosystems but also for carbon fixation as blue carbon. However, the national decline in eelgrass meadows in Japan, which was initiated by economic growth in the 1980s, prompted the implementation of conservation measures. This study explored the fundamental techniques of the sediment environment to enhance Zostera marina seed germination rates. We investigated the microbial origin of Zostera marina seeds under anaerobic conditions and assessed their germination efficiency. Anaerobic sediments in the eelgrass meadows were found to increase eelgrass germination rate by 6% more than aerobic sediments. And interestingly, the sulfate-reducing bacteria Desulfovibrionaceae and Sulfurospirillaceae were detected mainly on eelgrass seeds. Our result clearly indicated that the sulfate-reducing bacteria around Zostera marina seeds create anaerobic conditions that promote germination through their sulfate-reducing function. Therefore, when developing new eelgrass meadows, it can be expected to improve germination rates by preparing the sediment environment to facilitate the increase of SRB coexisting with seeds. However, the difference in bottom sediment conditions varies by region, so it is necessary to be careful when adding or removing something. In addition, germination and growth of eelgrass must be considered separately, and factors that promote growth are not described in this work. The result of this study was an important finding for the implementation of Blue Carbon activities to improve sediment quality prior to the creation of eelgrass meadows and can also support eelgrass meadows maintenance after establishment.